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Pass Labs X350.5 Stereo Amplifier Conclusions


My time with thX350.5.jpge Pass Labs X350.5 two-channel amplifier has been a marvel both sonically and visually.  Anytime a visitor would stop by they would literally pause as the sheer beauty and size of this amplifier caught their attention.  It portrays a commanding presence and is built like a tank, pegging the scale in the pride of ownership department. Its pristine sonic virtues, ability to drive even the most challenging of speaker loads beyond reference levels, is even more impressive than its overall excellent bench test results.

About the only thing I can ding physically on the X350.5 is its somewhat thin top cover plate as it doesn’t make a deadening thud when you tap on it.  I would have liked to have seen a slightly heavier gauge metal used or at least some sort of dampening lining the sheet to sonically deaden it.  While I don’t think this would in any way affect the sonic attributes of the amplifier, it does boost the pride in ownership factor which this amp already has in droves.  I’m just picking nits here of course, but it is not, after all, an inexpensive amplifier.

Incredible looks, pristine fidelity, plenty of juice, the Pass Lab’s X350.5 will surely satisfy even the most discriminating listener.  It took me over two months of listening to commit anything to writing as I was enjoying my experience with this amplifier that much.  I am confident Optimus Prime would be equally impressed with this amplifier.  Audioholic  & Audiophile Recommended!

Pass Labs Electronics

Pass Laboratories
24449 Foresthill Rd.
Foresthill, CA 95631 USA



X350.5 Review
MSRP: $11k

The Score Card

The scoring below is based on each piece of equipment doing the duty it is designed for. The numbers are weighed heavily with respect to the individual cost of each unit, thus giving a rating roughly equal to:

Performance × Price Factor/Value = Rating

Audioholics.com note: The ratings indicated below are based on subjective listening and objective testing of the product in question. The rating scale is based on performance/value ratio. If you notice better performing products in future reviews that have lower numbers in certain areas, be aware that the value factor is most likely the culprit. Other Audioholics reviewers may rate products solely based on performance, and each reviewer has his/her own system for ratings.

Audioholics Rating Scale

  • StarStarStarStarStar — Excellent
  • StarStarStarStar — Very Good
  • StarStarStar — Good
  • StarStar — Fair
  • Star — Poor
Frequency Response LinearityStarStarStarStarStar
Measured Power (8-ohms)StarStarStarStarStar
Measured Power (4-ohms)StarStarStarStarStar
Multi-channel Audio PerformanceStarStarStarStarStar
Build QualityStarStarStarStarStar
Fit and FinishStarStarStarStarStar
Ergonomics & UsabilityStarStarStarStarStar
About the author:
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Gene manages this organization, establishes relations with manufacturers and keeps Audioholics a well oiled machine. His goal is to educate about home theater and develop more standards in the industry to eliminate consumer confusion clouded by industry snake oil.

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Recent Forum Posts:

Rich Davis posts on October 12, 2013 16:33
There a LOT of VERY expensive amps on the market. In terms of how loud they go? Any good amp will probably drive most speakers past what is considered normal listening levels. I don't know if you've done any dB checks, but most of the time I only have my system at around 85 to MAYBE 95 dB on a continual basis. Anything louder than that is not typically good for your ears to have a system operating much louder than that. Most systems playing at that volume level are not using maximum output. Some speakers can handle large amounts or need large amounts of power to drive. Electrostatic, MBL, and other speakers might require or like large amounts of power, but in most cases, you'll probably not use much more than 20 or 50 watts, especially if you do things like bi-amping.

Don't judge a system by how loud it goes, since most of these places won't even turn up the system to maximum levels, because you can't sit within 60 feet of the speakers when they drive them to maximum spl. I have a pair of Meridian DSP5500s for mains, a DSP5000 center channel, with some other DevTech rears and a Talon sub and I can't sit in the same room after I turn up the volume knob past a certain point. Listening to a system in the 100+dB range is just not something good for your ears. When you go to a concert, break out your smartphone and a dB meter app and see what the dB is at your listening position.

Go to these sites and check out some of the most insane systems available. HigherFi - Worlds Best HiFi High-End Speakers and Audio or HIGH-END PALACE - The place for the world's best music systems!

And $50K for a pair of monoblocks isn't the high end, it's not more mid high end in terms of price. one can spend upwards of $500K for the Pivetta Opera or $200K for the Goldmund Telos 5000's, etc. so $50K for a pair of Pass is pretty cheap. :-)
Rich Davis posts on October 12, 2013 16:23
Pass makes nice stuff

Personally, when it comes to power amps, there are so many good amps out there and it's all a matter of matching up with the pre amp, cables, and speakers to achieve the desired end result.
Irvrobinson posts on October 26, 2012 23:21
surveyor, post: 917475
In the fact that it's more powerful than either the Mark Levinson or the ATI amps says it all- it truly a beast!

Actually, both the Levinson and the X350.5 are both merely in the middle of the respective manufacturers' product lines. If you want to get really silly with amplifiers both companies will fully accommodate you. Pass makes an X1000.5, and Levinson makes the completely ridiculous No53 monoblocks for $50K per pair. The Pass Labs monster is a comparative bargain at only about $35K per pair.
surveyor posts on October 26, 2012 22:00
gene, post: 917055
Yep an amp spends most of its time operating at low power so it's good to see how quite and clean it is there.

No doubt the ATI amp is a good one but it's not as powerful as the Pass Labs.

Using square waves to test an amp has little value these days when you can power sweep from 10-20kHz and beyond with modern test equipment.

The Pass Lab's amp displayed extreme linearity at all power levels for the entire audio band.

In the fact that it's more powerfull than either the Mark Levinson or the ATI amps says it all- it truly a beast!
craig7 posts on October 26, 2012 21:37
wow you guys reviewed a product ive actually seen in person before
and yeah… it is a pretty beast amp. ive never heard any system louder than it… it was incredible
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